The original manuscript is extant here and reads desires. Oliver Cowdery, when he copied the text from 𝓞 into 𝓟, replaced the plural desires with the singular desire. All the printed editions have followed the reading in 𝓟. As discussed under Mosiah 18:10, 11, the critical text will in each instance of desire(s) follow the reading of the earliest textual sources, thus desires here in Alma 49:26 since 𝓞 reads that way.
Summary: Restore the plural desires in Alma 49:26, the reading of the original manuscript.